【摘要】 为响应复杂环境中核武器运输炸药爆炸事故,建立了事故源项计算模型,根据两种典型运输事故场景特点,采用高斯多烟团模型数值模拟了气溶胶扩散过程,以文献试验数据为算例验证模型的有效性,讨论了影响计算的时间步长因素,并输入变风向的气象条件计算了有关辐射特征量。结果表明,1 kg武器级钚在53.52 kg TNT炸药爆炸下产生933 g 239Pu气溶胶,形成柱状云时高度可达249 m,气溶胶质量从顶部向下逐渐减小。时间步长为10 s以内时时间积分活度浓度计算结果曲线平滑,在中性气象条件下(风速6 m/s,东北风变东风),钚气溶胶预期剂量为10 mSv的下风向区域达2.8 km,污染区随风向改变而改变。模拟计算具有动态时效性和适应性,可用于核武器运输中炸药爆炸事故应急的后果评价。更多还原

【Abstract】 This paper aims to introduce a numerical simulation of aerosol dispersion with the explosive’s detonation in the process of nuclearweapon transportation.For this purpose,we have first of all made a description of the phenomenon of aerosol dispersion and explosives detonation accidentswith the nuclearweapon transportation in different environments.The most important features of the plutonium aerosol dispersion in the atmosphere is quickness and in turn demands quick response,which makes the dispersion quite different from that in other accidents in transportation.Therefore,we have made a summary of the calculation data of the accident source from the historical documents on the American early weapon safety tests.Referring to the said reference documents,we have established and validated the source model,and applied itto calculate the amount and the distribution of the plutonium aerosol in high explosives detonation accidents.Whenwe used the Gaussianmutilpuff dispersionmodel to simulate the aerosol dispersal based on the characteristics of the two typical accident scenarios,we have noticed that one of the characteristic features is instantaneous release and the other is that the release is done in a continuousway for a short instant of time.The aerosol can actually split in the vertical direction in instantaneous release scenario and the split that is in a manner of continuous release if it were leaked out.Then,we have made our evaluation of the dispersion model by comparing the results of the experimental data from the reference documents over the experiments done by us before.And,next,we have discussed the time step size that affects the simulation efficiency.Finally,we have worked out the physical quantity of the radiation by using the dynamic wind condition as the data input.According to the different intervention levels in the nuclear accidents,itwould be possible to figure out the plutonium aerosol distribution on the ground.And,then,all the models have to be translated into the computer codes whose numerical simulation can be more efficient.The simulation results demonstrate that 1 kgweapon grade plutoniumwould produce 933 g plutonium-239 aerosol,about 20% of which is inhalable in a 53.52 kg TNTdetonation accident.The aerosol mass distribution tends to decrease with the increase of the height of explosive plume.The integrated activity curve may resultfrom the time step size in less 10 s for the input is usually smoother than the curve from the bigger one.In normalweather,when the wind direction changes,the velocity would be 6 m/s at stability of class` D’.The plutonium aerosol tends to disperse downwind in a speed of 2.8 km,in which the expected dose is 10 mSv.The input of the optimal time step size is 10 s.The numerical simulation helps to provide the information on the source term,trajectory and aerosol distribution.更多还原